/**
* Fill in loop control fields
*
- * Based on analysis of loop variables, this function tries to remove sequences
- * in the loop of the form
+ * Based on analysis of loop variables, this function tries to remove
+ * redundant sequences in the loop of the form
*
* (if (expression bool ...) (break))
*
- * and fill in the \c ir_loop::from, \c ir_loop::to, and \c ir_loop::counter
- * fields of the \c ir_loop.
- *
- * In this process, some conditional break-statements may be eliminated
- * altogether. For example, if it is provable that one loop exit condition will
+ * For example, if it is provable that one loop exit condition will
* always be satisfied before another, the unnecessary exit condition will be
* removed.
*/
extern bool
-unroll_loops(exec_list *instructions, loop_state *ls, unsigned max_iterations);
+unroll_loops(exec_list *instructions, loop_state *ls,
+ const struct gl_shader_compiler_options *options);
+
+ir_rvalue *
+find_initial_value(ir_loop *loop, ir_variable *var);
+
+int
+calculate_iterations(ir_rvalue *from, ir_rvalue *to, ir_rvalue *increment,
+ enum ir_expression_operation op);
/**
public:
class loop_variable *get(const ir_variable *);
class loop_variable *insert(ir_variable *);
+ class loop_variable *get_or_insert(ir_variable *, bool in_assignee);
class loop_terminator *insert(ir_if *);
exec_list terminators;
/**
- * Hash table containing all variables accessed in this loop
+ * If any of the terminators in \c terminators leads to termination of the
+ * loop after a constant number of iterations, this is the terminator that
+ * leads to termination after the smallest number of iterations. Otherwise
+ * NULL.
*/
- hash_table *var_hash;
+ loop_terminator *limiting_terminator;
/**
- * Maximum number of loop iterations.
- *
- * If this value is negative, then the loop may be infinite. This actually
- * means that analysis was unable to determine an upper bound on the number
- * of loop iterations.
+ * Hash table containing all variables accessed in this loop
*/
- int max_iterations;
+ hash_table *var_hash;
/**
* Number of ir_loop_jump instructions that operate on this loop
loop_variable_state()
{
- this->max_iterations = -1;
this->num_loop_jumps = 0;
this->contains_calls = false;
this->var_hash = hash_table_ctor(0, hash_table_pointer_hash,
hash_table_pointer_compare);
+ this->limiting_terminator = NULL;
}
~loop_variable_state()
/** Are all variables in the RHS of the assignment loop constants? */
bool rhs_clean;
- /** Is there an assignment to the variable that is conditional? */
- bool conditional_assignment;
+ /**
+ * Is there an assignment to the variable that is conditional, or inside a
+ * nested loop?
+ */
+ bool conditional_or_nested_assignment;
/** Reference to the first assignment to the variable in the loop body. */
ir_assignment *first_assignment;
unsigned num_assignments;
/**
- * Increment values for loop induction variables
+ * Increment value for a loop induction variable
*
- * Loop induction variables have a single increment of the form
- * \c b * \c biv + \c c, where \c b and \c c are loop constants and \c i
- * is a basic loop induction variable.
+ * If this is a loop induction variable, the amount by which the variable
+ * is incremented on each iteration through the loop.
*
- * If \c iv_scale is \c NULL, 1 is used. If \c biv is the same as \c var,
- * then \c var is a basic loop induction variable.
+ * If this is not a loop induction variable, NULL.
*/
- /*@{*/
- ir_rvalue *iv_scale;
- ir_variable *biv;
ir_rvalue *increment;
- /*@}*/
+
+
+ inline bool is_induction_var() const
+ {
+ /* Induction variables always have a non-null increment, and vice
+ * versa.
+ */
+ return this->increment != NULL;
+ }
inline bool is_loop_constant() const
{
const bool is_const = (this->num_assignments == 0)
- || ((this->num_assignments == 1)
- && !this->conditional_assignment
+ || (((this->num_assignments == 1)
+ && !this->conditional_or_nested_assignment
&& !this->read_before_write
- && this->rhs_clean);
+ && this->rhs_clean) || this->var->data.read_only);
/* If the RHS of *the* assignment is clean, then there must be exactly
* one assignment of the variable.
assert((this->rhs_clean && (this->num_assignments == 1))
|| !this->rhs_clean);
- /* Variables that are marked read-only *MUST* be loop constant.
- */
- assert(!this->var->read_only || (this->var->read_only && is_const));
-
return is_const;
}
+
+ void record_reference(bool in_assignee,
+ bool in_conditional_code_or_nested_loop,
+ ir_assignment *current_assignment);
};
class loop_terminator : public exec_node {
public:
+ loop_terminator()
+ : ir(NULL), iterations(-1)
+ {
+ }
+
+ /**
+ * Statement which terminates the loop.
+ */
ir_if *ir;
+
+ /**
+ * The number of iterations after which the terminator is known to
+ * terminate the loop (if that is a fixed value). Otherwise -1.
+ */
+ int iterations;
};
projects / mesa.git / blobdiff